One trend in modern surgery is the trend toward minimally-invasive procedures, in which laparoscopic or endoscopic procedures are used. These procedures tend to be less invasive to the patient, using a body orifice or a puncture into a body cavity or a natural existing space as an entry point for a medical device. Examples of entry points include a component of the urinary tract or the gastrointestinal system. These procedures are used in order to avoid major incisions for surgical access, accomplishing the medical procedure in less time with less risk to the patient, and with reduced patient convalescence.
Minimally invasive procedures thus provide benefits to the patient, in the sense that the procedures may be accomplished more quickly and more economically, and with less discomfort and less overall invasion of the body when compared to traditional open surgical techniques. Minimally-invasive procedures are not without their problems, however. One significant problem is that body orifices tend to be small, and thus minimally invasive surgical procedures may be difficult to accomplish due to the very small access provided. For example, when entering the urinary tract, space in the ureter is very limited, since this passage is only several millimeters in diameter. As a result, the majority of minimally invasive procedures are performed with an endoscope, particularly ureteroscopes in urinary tract cases. These ureteroscopes typically have a working channel that limits instruments or surgical tools to a diameter of about 3 Fr (1 mm).
Accordingly, remotely operable medical devices have been developed that have a working portion on a distal end of the device and a control portion on the proximal end of the medical device. The distal end portion can be threaded through the small working channel of endoscopes or similar instruments to allow for operation of the working portion with the proximal end portion of the medical device extending out of the patient through the endoscope. The working portions of the medical devices may be pivotable forceps jaws, movable graspers, baskets, cutters, snares or other types of tools that are selectively used to obtain a biopsy or tissue sample for a patient, or otherwise remotely perform a specific task when inserted into a patient. With reference to an example medical device shown in FIG. 11, the working portions of these medical devices may be substantially larger than the proximal end control portion of the medical device to allow for taking larger biopsies or tissue samples than would be possible if the working portion was substantially the same size as the proximal end portion of the device.
Because the jaws of the forceps may be significantly larger than the proximal end portion of the medical device, the proximal end portion of this type of medical device must be back loaded into an endoscope, or similar instrument. In other words, proximal end portion of the medical device is inserted into the front end of the endoscopic instrument prior to the instrument being manipulated within the patient. A representative example of a back loading endoscopic instrument suitable for use with the handle disclosed in this specification was disclosed in U.S. Ser. No. 11/020,328 filed on Dec. 22, 2004, titled “Back Loading Endoscopic Instruments,” and is assigned to a related subsidiary of the assignee of this application, and is fully incorporated by reference herein in its entirety.
In operation, with reference to an exemplary forceps medical device shown in FIG. 11, when a proximal end 804 of a medical device 800 is inserted into an endoscope, or similar instrument, the proximal end 804 of the medical 800 normally extends out of the proximal, or rear end, of the endoscope to allow for operation of the forceps biopsy cups, or jaws 810 by the physician. Typically, the control, or proximal end, portion of the forceps medical device 800 includes a central wire 820 and an outer sheath 830, both of which are operatively connected to a pair of biopsy cups 810 that pivot within a housing 814. Central wire 820 and outer sheath 830 are joined together at the proximal end portion 804 of the forceps medical device 800. When the outer sheath 830 and the central wire 820 are in a relaxed state, the forceps jaws 810 are biased away from each other in a relaxed position. When the outer sheath 830 is placed in tension, or stretched, with respect to the central wire 820, the biopsy cups 810 rotate toward each other (in a biased position) against the biasing force of the housing 814 to obtain a tissue sample, or biopsy from the patient. When tension in the outer sheath 830 is released, the biopsy cups 810 extend away from each other due to the biasing force of arms that extend from the biopsy cups 810 and return to the relaxed position.
Often during medical procedures, medical devices that are used with an endoscope are inserted into the appropriate location within the patient through an access sheath. Additionally, to minimize the amount of discomfort and damage done by the working or operable portion of the medical device as it is advanced to the desired location, it is preferred to insert the device within the patient with the working portion in a closed, or biased, position, rather than an open, or relaxed, position. With continued reference to FIG. 11 and as discussed above, biopsy cups 810 are transferred to the closed position (i.e. the biopsy cups 810 rotate toward opposite jaws 810 until they contact each other) when the outer sheath 830 is held in tension with respect to the central wire 820.
To maintain the biopsy cups 810 in the closed position, the physician or another medical professional must manually maintain the stretch in the outer sheath 830 as the working portion of the medical device is advanced to the desired location within the patient. Because it often takes a significant period of time to properly position the medical device in the patient, it is often a labor intensive and tiresome procedure to maintain the outer sheath 830 in tension to ensure that the biopsy cups 810 remain in the closed position during the insertion and also during operation and removal. Accordingly, it is desired to obtain a mechanism that can maintain the operable portion of a medical device in a closed position without requiring a medical professional to manually maintain the outer sheath stretched during insertion, placement, operation, and removal of the medical device 800 and the endoscopic instrument within the patient.